Engine starting fluid



7 United States Patent 3,108,864 ENGINE STARTING FLUID Maurice R. Barusch, Richmond, Calif, amignor to California Research Corporation, San Francisco, Calif, a corporation of Delaware N0 Drawing. Filed .luly 13, 1960, Ser. No. 42,496

1 Claim. (CI. 4453) The present invention relates to an improved starting fluid for use in internal combustion engines under subfreezing ambient temperature conditions.

Unimpeded starting of internal combustion engines at subfreezing temperatures became a problem of considerable importance since the establishment in recent years of numerous military bases and Weather stations in the Arctic and Antarctic regions. Special priming or starting fluids have been proposed in the past as aids for initiating ignition at relatively low temperatures prevalent in winter in the temperate climates. Among these aids, diethyl ether is the best known and the most often used. However, even diethyl ether is not always satisfactory at subfreezing temperatures and generally fails to induce ignition at temperatures below 40 F.

I have now discovered that this failure of diethyl ether to ignite at subfreezing temperatures can be remedied by combining the ether with an effective amount, from about 5 to about 50% by volume, and preferably from about to about 25% by volume, of dimethyl peroxide.

The discovery that the highly volatile dimethyl peroxide can be safely employed to facilitate ignition of diethyl ether in starting internal combustion engines at subfreezing temperatures, when the ether alone is ineffectual, is entirely unexpected, if one considers the extreme explosiveness of pure dimethyl peroxide under the action of heat and particularly at the slightest impact or shock.

Dimethyl peroxide is a very mobile colorless gas which boils at 563 F. at 740 mm. and has a melting point of from -148 to -l50 F. It is extremely explosive and requires great care in handling.

It is known in the art that if one lets a drop of dimethyl peroxide contained in the liquid state in a cooled test tube fall on the floor, a very violent explosion occurs. As a matter of fact, even the vapor of dimethyl peroxide, with or without air, is extremely sensitive to shock and can even be brought to explode by being shaken in an inert gas. Contrary to this, I have found that solutions of less than 25% by volume of dimethyl peroxide in diethyl ether do not explode when struck by a sixty pound weight from a distance of three feet.

In order to ascertain more closely the explosion tendencies of solutions of dimethyl peroxide in diethyl ether, a series of experiments were carried out. In the course of these experiments, a small sealed glass test tube of 8 mm. I.D., containing a blasting cap (dynamite) and connected by wires to a source of an electrical spark for initiating explosion, was placed inside another glass tube 6 inches in length and of 16 mm. OD. The space in the second tube, unoccupied by the tube containing the blasting cap, was filled with 10 ml. of the starting fluid to be tested, and the second tube was then sealed off. This glass tube system was placed inside a lead pipe 7 inches long, having an CD. of 3 .38 cm. and ID. of 1.8 cm.

In each test, after the blasting of the dynamite cap, the maximum average bulge in the diameter of the bomb obtained on the protective lead pipe was measured and recorded, and the occurrence of detonation and fire, if perceptible, noted. The results of these tests are shown in the following Table I.

, 3,108,864 Patented Oct. 29, 1963 Table I Run Vol. Percent of Diameter No. Peroxide of Bulge, Observation 1 (diethyl ether alone) 4. 28 N0 Detonation, No Fire. 2"..- 10.45% 4. 20 Do.

4.19 No Detonation, Fire. 4. 38 D0. 4. 55 Do. 4. 64 Detonated, Fire. 5. 28 Do.

The above results point out that diethyl ether solutions containing less than about 25% by volume of dimethyl peroxide are comparatively safe to handle, (runs Nos. 2-5), and that, particularly, those solutions, containing from about 20 to about 5% by volume do not give rise to explosion hazards.

These findings suggested the possibility of a safe preparation of dimethyl peroxide for the subsequent use in combination with diethyl ether as a starting fluid for initiating ignition in internal combustion engines at low subfreezing temperatures in accordance with the invention. In an illustrative example of such a preparation, a reaction flask, externally cooled in ice water, received a charge of 0.36 mol of dimethyl sulfate, and then a 30% aqueous solution of 0.18 mol of hydrogen peroxide was added through a funnel over a period of live minutes, while stirring intensively with nitrogen gas. Thereafter, a solution of 22.4 g. of potassium hydroxide in 50 ml. of water was added over a period of 7 to 8 minutes. Dimethyl peroxide formed in the resulting reaction was transferred through a side-arm of the reactor into a receiver flask where it was kept under reflux, while being cooled with dry ice-acetone mixture. A total of 8 ml. of dimethyl peroxide was collected in the receiver and comibned with a charge of 7 ml. of diethyl ether (this corresponded to a concentration of 58% by volume of dimethyl peroxide in the ether.)

Once the solution of dimethyl peroxide in the ether is prepared, it can be reduced to the desired concentration by adding thereto more diethyl ether, whereupon the necessary amounts can be measured volumetrically and transferred to appropriate cartridges, capsules or bulbs for use in the priming of internal combustion engines. A large variety of such bulbs and cartridges suitable for priming either spark-ignition or compression-ignition engines at low temperature conditions have been described in the past. Several US. patents, among them Nos. 2,601,211 and 2,730,093, issued to Neely, and No. 2,516,787, issued to Moody, disclose different embodiments of such cartridges or bulbs and different devices and systems for the introduction (injection) of their contents into the air intake manifold and thence into the combustion chamber of an engine. When a solution of diethyl ether containing from about 5 to 20% by volume of dimethyl peroxide is employed as a starting fluid under subfreezing conditions, the minimum compression ratio required to sustain auto-ignition of diethyl ether is substantially lowered by a comparison with the minimum compression ratio required for initiating and sustaining auto-ignition of diethyl ether alone. Thus, while the minimum compression ratio at which diethyl ether alone is capable to auto-ignite is observed to be equal to 7.75, solutions in diethyl ether of 10% and 20% by volume of dimethyl peroxide auto-ignite at the compression ratio of 7.0.

The following test data illustrate the superiority of dimethyl peroxide solutions in diethyl ether as starting fluids over diethyl ether employed alone as a starting fluid. In these tests, a single-cylinder, valve-in-head, variable-compression spark-ignition CFR engine was employed, using methanol as the engine coolant. Engine jacket temperatures ranged from -8 F. to +6 F. while the engine was being cranked (motored) at 600-r.p.m. The spark plug was removed from the engine, so that ignition, when it occurred, was due to compression. The starting fluids were introduced into the engine from small metal bombs through a connection controlled by a hand valve and screwed onto the engines manifold near the intake port. The bombs were steel cylinders, 30 ml. in capacity, each containing 10 ml. of the starting fluid pressurized into the bomb with nitrogen to 275 psi.

The surrounding temperature was equal to about 68 F. and the temperature of the inlet-air was between 6265 F. The minimum compression ratios for each particular priming fluid were observed by ear, and the temperature of the exhaust gases was also'recorded to get an idea of the completeness of combustion.

Run Oom- Jacket Exhaust Perform- No. Starting Fluid pression Temp, Temp, ance Ratio F. F.

1 Diethyl Ether 8. 5 50-90 Fire. 2 8. 0 0 50-90 Do. 7. 75 8 40-65 D0. 7. 75 4 40-80 D0. 7. 75 +4 55-80 D0. 7. 5 8 40-60 No Fire 7. 5 0 50-65 Do, 7. 5 +6 63-70 D0. 7. 25 -4 50 DO. 7. 25 2 45 Do. 7. 0 -4 45-60 D0. (1 7. 0 2 40 D0. 10% Dimethyl Per- 7. 00 2 40-80 ire.

oxide in Diethyl Ether Solution. 14 20% Dimethyl Per- 7.00 6 45-75 Do.

oxide in Diethyl Ether Solution. 15 d0 7. 00 4 45-70 Do.

It is readily noted from the above results that solutions ofdimethyl peroxide in diethyl ether, when employed in accordance with the present invention, auto-ignited at compression ratios at least 0.75 lower than the ratios at which diethyl ether used alone auto-ignites in the combustion chamber of an engine.

Because of its great volatility (B.P.=56.3 F. at 740 mm.), dimethyl peroxide is particularly suitable for use at temperatures below R, which bring about so much difficulty in engine starting in the extreme northern and southern latitudes.

Very little risk is ofiered by the use of bulbs or cartridges containing solutions of dimethyl peroxide in diethyl ether, as cold-weather starting fluids in accordance with the invention.

Although certain variations in the eifectiveuess of the starting fluid combination of the invention may occur due to its use in different types of internal combustion engines and to different speeds of cranking, as well as .on account of the different methods and rates of introduc ing the starting fluid into an engine, these variations are considered to be minor and will not exceed the scope of the invention as it is defined in the following claim.

What is claimed is:

A starting fluid composition for use in internal combustion engines under subfreezing temperature conditions and particularly at temperatures below 40 B, said composition consisting essential of diethyl ether and from about 10 to about 25% by volume of dimethyl peroxide.

References Qited in the file of this patent UNITED STATES PATENTS 2,092,322 Moser Sept. 7, 1937 2,093,008 Egerton Sept. 14, 1937 2,431,322 Goodale Nov. 25, 1947 2,575,543 Young Nov. 20, 1951 2,655,440 Barusch et al. Oct. 13, 1953 2,912,313 Hinkamp et al. Nov. 10, 1959 2,934,048 Young Apr. 26, 1960 

